The course
The timeline of events *'8:46 AM': Flight 11 crashes into the WTC (World Trade Center) north tower. *'8:46:40': Flight 11 crashes at roughly 490 mph (790 km/h) into the north side of the north tower of the World Trade Center, between floors 94 and 98. The aircraft enters the tower mostly intact. It plows to the building core, severing all three gypsum-encased stairwells, dragging combustibles with it. A massive shock wave travels down to the ground and up again. The combustibles and the remnants of the aircraft are ignited by the burning fuel. Since the building lacks a traditional full cage frame and depends almost entirely on the strength of a narrow structural core running up the center, the fire at the center of the impact zone is in a position to compromise the integrity of all internal columns. Two home video cameras are known to have recorded the impact. People below the severed stairwells in the north tower start to evacuate; no-one above the impact zone is able to do so. *'8:46 to 10:29': At least 100 people (some accounts say as many as 250), primarily in the north tower, trapped by fire and smoke in the upper floors, jump to their deaths. There is some evidence that large central portions of the floor near the impact zone in the north tower collapsed soon after the plane hit, perhaps convincing some people that total collapse was imminent. One person at street level, firefighter Daniel Thomas Suhr, is hit by a jumper and dies. No form of airborne evacuation is attempted as smoke is too dense for a successful landing on the roof of either tower. *'9:03 AM': Flight 175 crashes into the south WTC tower. *'9:03:13': Flight 175 crashes at about 590 mph (950 km/h) into the south side of the south tower, banked between floors 78 and 84. By this time, several media organizations are covering the first plane crash; millions see the impact live. Parts of the plane leave the building at its east and north sides, falling to the ground six blocks away. A massive evacuation begins in the south tower below its impact zone. One of the stairwells in the south tower remains unblocked, but filled with smoke. This led many people to mistakenly go upwards towards the roof for a rooftop rescue that never came. CNN's headline now reads 'Second plane crashes into World Trade Center'. *'9:59 AM': The south tower of the World Trade Center collapses. *'9:59:04': The south tower of the World Trade Center collapses, viewed and heard by a vast television and radio audience. It had stood for 56 minutes 10 seconds since the impact by Flight 175. As the roar of the collapse goes silent, tremendous gray-white clouds of pulverized concrete and gypsum rush through the streets. Most observers think a new explosion or impact has produced smoke and debris that now obscures the south tower. When the wind finally clears the immediate space, it is plain to see that there is no tower. *'10:28 AM': The World Trade Center north tower collapses. *'10:28:31': The north tower of the World Trade Center collapses from the top down, as if being peeled apart. Probably due to the destruction of the gypsum-encased stairwells on the impact floors (most skyscraper stairwells are encased in reinforced concrete), no one above the impact zone in the north tower survives. The Marriott Hotel, located at the base of the two towers, is also destroyed. The second collapse is also viewed live on television and heard on radio. *The north tower, 1 WTC, stood for 102 minutes 5 seconds after impact. The south tower, 2 WTC, collapsed about 56 minutes later. Full timeline Impact of the airliners *The towers were struck by hijacked Boeing 767 jet planes, American Airlines Flight 11 and United Airlines Flight 175. *A typical Boeing 767 is 180 feet (55 m) long and has a wingspan of 156 feet (48 m), with a capacity of up to 24,000 US gallons (91,000 l) of jet fuel. *The planes hit the towers at very high speeds. Flight 11 was traveling roughly 490 mph (790 km/h) when it crashed into the 1 WTC, the north tower; flight 175 hit 2 WTC, the south tower, at about 590 mph (950 km/h). *The resulting explosions in each tower ignited 10,000 gallons (c. 40,000 l) of jet fuel and immediately spread the fire to several different floors while consuming paper, furniture, carpeting, computers, books, walls, framing and other items in all the affected floors. *The jet fuel probably burned out in less than 10 minutes; the contents of the buildings burned over the next hour or hour and a half, according to the lead investigator of the NIST investigation. Various facts *The youngest passenger on the hijacked jets was Christine Hanson on United Airlines Flight 175. She was 2 and on her first trip to Disneyland. *The oldest passenger on the hijacked jets was Robert Norton on American Airlines Flight 11. He was 82. *The New York City Fire Department lost 343 firefighters, almost half the number of on-duty deaths in the department's 100-year history. *The south tower collapsed at a magnitude of 2.1 on a seismograph; the north tower collapsed with a magnitude of 2.3, according to Columbia University in New York. *91 baseball games were postponed in the six days Major League Baseball suspended play, the longest postponement, excluding work stoppages, for regular-season games since World War I in 1918. *Sirius, one of the first bomb-sniffing K-9 dogs stationed near the World Trade Center after the 1993 terrorist bombing, died in the Sept. 11 attacks. *Fifteen million square feet of office space was lost at the WTC, more than three times the amount of space at the Sears Tower in Chicago. 1,430 people with 50,000 employees from 26 countries called the WTC "the office." *1,337 vehicles were crushed when the towers collapsed, including 91 FDNY vehicles - a little more than half of all the fire vehicles in Louisville. *1.5 million working hours during 261 days were spent removing the debris at the WTC site. *Seven in 10 Americans say they have experienced depression since the attacks. New York State Office of Mental Health estimates more than 33,000 showed symptoms of post-traumatic stress disorder. *America's Blood Centers, a network of community banks, collected 251,370 units, nearly three times the normal intake, in the four days after Sept. 11. The Red Cross collected more than 200,000 units and saw its on-hand supply nearly double, from 80,000 units to 156,000 units in days. *The fires at Ground Zero burned for 99 days, until Dec. 19. (Sources: USATODAY research by April Umminger, Joan Murphy, Lori Joseph, William Risser, Darryl Haralson, Mary Cadden)